Ignore protobuf schema when rustfmt is invoked

.gitignore

@@ -1,2 +1,3 @@
 Cargo.lock
 target/
+src/proto/proof.rs

Cargo.toml

@@ -18,6 +18,7 @@ categories    = ["data-structures", "cryptography"]
 
 
 [dependencies]
+cfg-if = "0.1.3"
 ring = "^0.12.0"
 protobuf = { version = "1.7.1", optional = true }
 serde = { version = "^1.0.55", optional = true }

src/lib.rs

@@ -1,21 +1,28 @@
-#![deny(
-    missing_docs, unused_qualifications, missing_debug_implementations,
-    missing_copy_implementations, trivial_casts, trivial_numeric_casts, unsafe_code,
-    unstable_features, unused_import_braces
-)]
+#![deny(missing_docs, unused_qualifications, missing_debug_implementations,
+        missing_copy_implementations, trivial_casts, trivial_numeric_casts, unsafe_code,
+        unstable_features, unused_import_braces)]
 
 //! *merkle* implements a Merkle Tree in Rust.
 
+#[macro_use]
+extern crate cfg_if;
 extern crate ring;
 
-#[cfg(feature = "serialization-protobuf")]
-extern crate protobuf;
+cfg_if! {
+    if #[cfg(feature = "serialization-protobuf")] {
+        extern crate protobuf;
+        #[allow(unused_qualifications)]
+        mod proto;
+    }
+}
 
-#[cfg(feature = "serialization-serde")]
-extern crate serde;
-#[cfg(feature = "serialization-serde")]
-#[macro_use]
-extern crate serde_derive;
+cfg_if! {
+    if #[cfg(feature = "serialization-serde")] {
+        extern crate serde;
+        #[macro_use]
+        extern crate serde_derive;
+    }
+}
 
 mod merkletree;
 pub use merkletree::MerkleTree;
@@ -29,9 +36,5 @@ pub use hashutils::Hashable;
 mod tree;
 pub use tree::{LeavesIntoIterator, LeavesIterator};
 
-#[cfg(feature = "serialization-protobuf")]
-#[allow(unused_qualifications)]
-mod proto;
-
 #[cfg(test)]
 mod tests;

src/proof.rs

@@ -52,10 +52,8 @@ mod algorithm_serde {
 
     mod test {
         use super::*;
-        use ring::digest::{
-            SHA1 as sha1, SHA256 as sha256, SHA384 as sha384, SHA512 as sha512,
-            SHA512_256 as sha512_256,
-        };
+        use ring::digest::{SHA1 as sha1, SHA256 as sha256, SHA384 as sha384, SHA512 as sha512,
+                           SHA512_256 as sha512_256};
 
         static SHA1: &Algorithm = &sha1;
         static SHA256: &Algorithm = &sha256;

src/proto/mod.rs

@@ -1,4 +1,8 @@
-mod proof;
+cfg_if! {
+    if #[cfg(not(rustfmt))] {
+        mod proof;
+    }
+}
 
 use ring::digest::Algorithm;